SU1700081A1 - Mixture for modifying cast iron - Google Patents

Abstract

The invention relates to linear production, in particular, to modifier compositions for out-of-furnace treatment of cast iron with lamellar graphite. The purpose of the invention is to increase the mechanical properties in massive sections of differential castings and to ensure the uniformity of properties and structure over the sections, reducing the consumption of the mixture. The mixture for modifying h / guna, preferably with an increased carbon equivalent, contains the following components, wt%: high carbon ferrochrome 20-70; nitrated ferromanganese 10-40: ferroboron 5-40. 1 tab. (L

Description

FIELD OF THE INVENTION The invention relates to foundry, in particular, to modifier compositions for out-of-furnace treatment of cast iron with lamellar graphite.

The purpose of the invention is to increase the mechanical properties in massive parts of differential castings, to ensure the uniformity of properties and structure over sections and to reduce the consumption of the mixture.

SUMMARY OF THE INVENTION The essence of the invention is that the mixture for modifying cast iron with predominantly increased carbon equivalent and for differential castings, including a ferrochromic additive and nitrated manganese, additionally contains ferroboron, and as a ferrochromic additive it contains carbon-carbon ferrochrome, in the following ratio of components, wt.% : High Carbon Ferrochrome 20-70

Nitrided

manganese 10-40

Ferrobor5-40

Example. The test of the proposed mixture for the modification of cast iron is carried out upon receipt of a gas generator with a carbon equivalent of CE of 3.8-4.2% of the following composition, wt.%: Carbon 3.2-4.2, silicon 2.0-2.5; manganese 0.3-0.5.

As the starting components for the preparation of the proposed mixture, IC.

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The following materials are used: high-carbon ferrochrome FH800 (carbon content 5-8%), manganese nitrided MRnbA and ferroboron FB20.

Modifying mixtures are prepared as follows.

The initial ferroalloys were crushed in a cheek crusher to a particle size of not more than 5 mm and mixed in laboratory runners,

The original cast iron of the specified chemical composition is smelted from a mixture containing ultimate blast iron, steel, cm, return of production and ferroalloys.

Modifying doughs are introduced into the ladle by filling 1/5 of its capacity in quantities of 0.5-1% by weight of the melt to be treated at 1360-1400 ° C.

The effectiveness of modifying mixtures is estimated by the size of the iron on an ISO sample of 110x50x20 mm poured into the form of a core mixture with a metal plate, by tensile strength of cast iron on standard samples poured according to GOST 16818-85 and hardness in various sections. x massive step test with steps of thickness 30. 50, 70 and 100 mm.

The results of the study of the compositions of the proposed mixture are given in the table.

From the data presented in the table, it follows that the proposed composition of the modifying mixture (compounds 8-17} increase the strength of cast iron by 1.1-1.5 times as compared with the prototype and the uniformity of properties over the casting (scatter, hardness from The cut-in section is 4-14 HB, and the prototype is 16-29 HB), the chill-out value meets the technological standards (3-5 mm according to RTM 2MT2Q-5-85). At the same time, it should be noted that in the cast iron structure in all the casting sections a pearlite structure (PLO) with a uniform distribution of graphite (PGD 45-90) was obtained, and when used The mixture of the prototype in sections with a thickness of more than 50 mm in the structure is up to 20% ferrite, and the size of inclusions of graphite increases (PGd 180-360), as evidenced by the data on hardness,

When going beyond the proposed boundary values, there is no increase in the uniformity of properties over the casting section compared with the prototype (compositions 3-7) and strength (composition 3), and for compositions 5-7, the chill-out value exceeds the established technological norm; up to 8% of cementite, as evidenced by an increase in taernostm in thin sections.

The implementation of the invention permits the production of one base melt using an extra punching method to obtain 2-3 grades of cast iron for differential machine-building castings.

Claims (1)

Claims of the Invention A mixture for modifying cast iron, preferably with an increased carbon equivalent and for differential castings, including a ferrochromic additive and nitrated manganese, is so important that, in order to improve the mechanical properties of the massive parts of the differential castings, ensuring the uniformity of the properties and structure over the cross sections and reducing the consumption of the mixture, it additionally contains ferroboron, and as the ferrochromic additive it contains high carbon ferrochrome in the following ratio of components ov, wt,%: High carbon ferrochrome 20-70 Nitrided manganese 10-40 Ferrobor5-40